In this paper, we propose a new geographic routing algorithm that alleviates the effect of location errors on routing in wireless ad hoc networks. In most previous work, geographic routing has been studied assuming perfect location information. However, in practice there could be significant errors in obtaining location estimates, even when nodes use GPS, hence existing geographic routing schemes will need to be appropriately modified. We investigate how such location errors affect the performance of geographic routing strategies. We incorporate location errors into our objective function by considering both transmission failures and backward progress. Each node then forwards packets to the node that maximizes this objective function. We call this strategy Maximum Expectation within transmission Range (MER). Simulation results with MER show that accounting for location errors significantly improves the performance of geographic routing. Our analysis also shows that our algorithm works well up to a critical threshold of error. We also show that MER is robust to the location error model and model parameters. Further, via simulations, we show that in a mobile environment MER performs better than existing approaches.

Date of this Version

December 2004